There are currently a variety of types of fuel cells, including alkaline fuel cells, phosphoric-acid fuel cells, molten carbonate fuel cells, solid oxide fuel cells, and proton exchange membrane fuel cells. For example, in an alkaline fuel cell, a cathode operates as a catalyst that creates hydroxide ions from water and oxygen in the atmosphere which is supplied. The hydroxide ions that are created pass through an electrolyte to an anode, which operates as a catalyst for reacting hydrogen with the hydroxide ions to form water. The fuel cell thus generates electromotive force through the reaction of fuel and air.
For example, Published Japanese Translation of PCT application, JP-T-4-502980, for example, describes electrocatalytic material which is particularly suitable as an electrode catalyst of an alkaline fuel cell. With this electrocatalytic material, fine activated carbon is used as the support material on which single-crystal gold particles having a (100) surface are then deposited. With the alkaline fuel cell described in the foregoing publication, the electrocatalytic particles are highly catalytically active and reduce oxygen to water or hydroxide, as well as reduce hydrogen peroxide ions to water when hydrogen peroxide ions are present.
However, gold, which is used as the electrocatalytic material, is an expensive metal. Therefore, if this kind of electrolytic material is used as the electrode catalyst, the cost of the fuel cell will likely increase. Hence, it is desirable to develop electrolytic material which is formed of a less expensive material yet which is highly catalytically active.
Also, particularly in the cathode, hydrogen peroxide ions may be formed the process of creating hydroxide ions from oxygen. Hydrogen peroxide ions are highly reactive so if they reach the electrolyte as they are, they may damage the electrolyte, causing it to deteriorate. Therefore, it is desirable to inhibit hydrogen peroxide ions formed in the cathode from reaching the electrolyte by trapping them or breaking them down in the cathode.